The present invention generally relates to an electric shaver and more particularly, to an inner blade for use in a reciprocating type electric shaver.
Conventionally, in reciprocating type electric shavers, it has been so arranged, for example, as shown in FIG. 1 that the inner blade comprises coupling pipes 13 and a plurality of inner blade elements 2 which are fixedly mounted, in parallel with each other, on the coupling pipes 13 after insertion of the coupling pipes 13 through corresponding coupling holes of each of the inner blade elements 2 so as to be brought into sliding contact with an inner surface of a fixed outer blade 1. The inner blade elements 2 are manufactured by subjecting a metallic sheet to press working. Furthermore, a groove portion 3 is formed on each of opposite faces of the inner blade element 2 by press working such that a rake angle .theta. for improving cutting efficiency of hairs is provided at each of opposite blade tip portions 4. It is desirable to increase the rake angle .theta. as much as possible in order to increase the cutting efficiency of hairs. However, in order to increase the rake angle .theta., thickness of the inner blade element 2 is required to be increased such that the inner blade element 2 can withstand pressure of press working for forming the groove portions 3. However, when the thickness of the inner blade element 2 is increased, total weight of the inner blade becomes large, thereby resulting in increase of power consumption of a drive source of the shaver. Thus, the rake angle .theta. formed on the inner blade element 2 made of a metallic sheet is restricted to a certain value.
Then, in order to solve the above described problem regarding the rake angle .theta., an inner blade element 5 comprising a pair of bent pieces 6 and 7 formed with blade tip portions 8 and 8', respectively has been developed as shown in FIG. 2. The pair of the bent pieces 6 and 7 are, respectively, provided with coupling holes 11 and 12 each receiving the coupling pipe 13 therein and are brought into contact with each other such that the blade tip portions 8 and 8' are directed in opposite directions remote from each other. In the case of the inner blade element 5, a large rake angle .theta. can be obtained easily by bending each of the blade tip portions 8 and 8' and further, total weight of the inner blade can be reduced due to small sheet thickness of the bent pieces 6 and 7. However, in order to assemble the inner blade elements 5 having such constructions into an inner blade, it has been so arranged as shown in FIG. 3 that the inner blade elements 5 each comprising the pair of the bent pieces 6 and 7 in close contact with each other, are fitted into corresponding slots 10 provided side by side, on an assembly stand 9, with the blade tip portions 8 and 8' being directed in opposite directions remote from each other. However, it is quite troublesome and extremely low in working efficiency to fit the pair of the bent pieces 6 and 7 into each of the slots 10 such that the pair of the bent pieces 6 and 7 are brought into close contact with each other, with the blade tip portions 8 and 8' being directed in opposite directions remote from each other. Furthermore, burr may be formed around peripheral edges of the coupling holes 11 and 12 of the respective bent pieces 6 and 7. In that case, as indicated by the arrow A in FIG. 3, it becomes impossible to align the coupling hole 11 with the coupling hole 12 accurately after the bent pieces 6 and 7 have been fitted into each of the slots 10, so that it becomes difficult to insert the coupling pipes 13 through the coupling holes 11 and 12. Moreover, since the bent pieces 6 and 7 are mounted on the coupling pipes 13 independently of each other through insertion of the coupling pipes 13 thereinto, such an inconvenience may arise that either one of the bent pieces 6 and 7 is moved in an axial direction of the coupling pipes 13 so as to be separated from the other one of the bent pieces 6 and 7 under improper conditions of punching of the coupling holes 11 and 12 and of an operation of inserting the coupling pipes 13 through the coupling holes 11 and 12. Furthermore, the inner blade elements 5 each comprising the pair of the bent pieces 6 and 7 have such a disadvantage that the bent pieces 6 and 7 tend to be caused to adhere to each other during heat treatment of the bent pieces 6 and 7 as shown in FIG. 4.